Kirkendall Void Formation During Selective Oxidation

Abstract

The selective oxidation of high Mn austenitic steel was investigated by transmission electron microscopy. The annealing resulted in a MnO surface layer and a Mn-depleted ferritic layer. At the MnO/steel interface, voids were formed between the a-xMnO center dot SiO2 and c-MnO center dot Al2O3 layers. This is the first time that void formation is observed during selective oxidation of steel. The Kirkendall voids grow and develop characteristic void surfaces because of the fast diffusion of MnO on the void surface.